So-called boat leveling devices of the trim-tab type have been known for many years and various forms of them have been developed in an effort to increase attitude control and stability of water crafts, as well as improving general hydrodynamic efficiency inclusive of decrease of flow velocity under the hull and fuel efficiency.
In a typical trim-tab system, the tabs themselves are controlled with an actuator device. Actuators types range from mechanical actuators, electrical actuators, electro-mechanical actuators, and hydraulic actuators. With every single actuation system in a trim-tab set up comes an inherent maximum force that the actuator can withstand. Take an electro-mechanical actuator for example, typically seen on a yacht of about 36 feet in length, where the electro-mechanical outfit uses a worm drive to raise and lower the actuator ram, which is in connection with a trim-tab, therefore putting the trim-tab in its desired angle of deflection. When the tab is in a down position, any angle other than zero degrees, the force of the water coming in contact with the tab increases with speed and higher angle of deflection. In this example, there are two trim-tabs and each having two actuators. The actuators for a watercraft of this length typically can withstand 3,500-4,000 pounds of force per actuator. If one of those trim-tab actuators were to fail, there is not much beyond the second actuator holding the tab in place, and this could begin to change deflection angle unexpectedly as the other actuator typically could not withstand the force. A need arises in a case such as this wherein a locking mechanism such as the present invention would prevent further issue with the loss of trim-tab system function where an actuator fails.
Currently in the art, the only way to lock a trim-tab in place is with the actuation device itself. Looking at the system in Weiler, U.S. Pat. No. 3,463,109 (1968), a trim tab system is shown to have a hydraulic actuator controlling the position of the angle of deflection. The hydraulic actuator is essentially what keeps the actuator in its place while the watercraft is in motion.
Another prior art trim-tab system is that which is disclosed in Crews, Jr., U.S. Pat. No. 5,881,666 (1997), teaches an electro-mechanical trim-tab system utilizing an electric motor to drive a gearbox and a threaded shaft in an actuator to raise and lower a ram to get the trim-tab to a desired angle of deflection. The gearbox and electric motor are what keeps the trim-tab in place while the watercraft is moving.
A third prior art trim-tab system in Pilger, U.S. Pat. No. 6,167,830 (1999), discloses a fully mechanical trim-tab actuator that uses an adjustment rod with a pivot hole to lock the trim-tab in its desired angle of deflection, with a screw and nut, at different points along the adjustment rod. This does not need the assistance of any hydraulic or electro-mechanical system.
What all three prior-art systems have in common is the use of the actuator itself to effectively lock the trim-tab in its desired place and it is not to move until the actuator is engaged to lift or drop the tab. What is lacking in all trim-tabs types of the likes above is a fail-safe, therefore creating a need. If the existing actuator in all three prior art systems were to fail, the trim tab will no longer be in its desired angle as it is free to move about the hinging point that is typical in a trim-tab system.
The instant invention discloses a trim-tab locking system. It is an object of the instant invention to provide a fail-safe for common trim-tab actuators in the event that there is an actuator failure.
The instant invention also sets forth to add strength to the overall trim-tab system and alleviate substantial stresses and forces that the actuator would be under without the instant invention.